Step 1 – Line a square tin with baking parchment.
Step 2 – Melt the butter in a sauce pan on a low heat.
Step 3 – Blitz the biscuits in a Blender (I used a Nutribullet).
Step 4 – Add the Brown Sugar and 300g of Peanut Butter to the biscuit mixture and stir well.
Step 5 – Once the butter has melted to liquid, add to the biscuit mixture and stir well (I used a Kitchen Aid).
Step 6 – Tip the mixture in a pre-lined tin, and use a silicone spatula to pat the mixture down tightly.
Step 7 – Break the Dark Chocolate and White Chocolate into small pieces and place in two separate bowls.
Step 8 – Melt the Chocolate in the microwave in 30 second spurts until melted.
Step 9 – Tip the Dark Chocolate onto the biscuit mixture and gently use a back of a spoon to spread.
Step 10 – Pour the White Chocolate in the middle of the Dark Chocolate, and use the end of a teaspoon to create a marbled swirl effect.
Step 11 – Place in the fridge to set for as long as possible – preferably 2 hours!